Agriculture Reference
In-Depth Information
In this chapter we generalise this approach by searching
successively over the grid of unitary tax exemptions and the grid of prices
of energy crops. Furthermore, capacities and industrial processes have been
included as variables in the industry model in order to have a more realistic
representation of possible bio-energy carriers configurations of the French
bio-fuel industry, illustrated for the wheat-to-ethanol and rape-seed-to-ester
processors
5
.
The model operates on two levels. First, the agricultural sector
regional problem is solved. A model determines the amount of crops
offered to the market for different sets of crop prices. Among these crops,
m
energy crops are processed by
n
bio-fuel systems. Then, the industry
model considers supply provided by the agricultural sector, and, given
unitary tax exemptions, proposes activity levels resulting in positive profits
for bio-fuel industry.
3.1 The agricultural sector model
A large number of sub-models each corresponding to a particular farm are
articulated in a staircase form to modelise the agricultural sector. The
agricultural sector model belongs to the MAORIE family of models (Carles
et al.
1997) and its specification is shown in Box 1. Farmers maximise
their gross margin subject to resource (arable land availability),
institutional (set aside obligation, sugar-beet quota) and agronomic (crop
rotation) constraints.
Box 1. Agricultural sector model specification
Indices
index for food crops, (
c=
1 for sugar beets)
index for energy crops (
D
= {wheat, rape-seed}),
index for farms
index for bio-fuels (
B =
{ethanol, ester}),
index for agronomic constraints
index for
m
-tuples of prices (for each energy crop)
Parameters
gross margin for food crop
c
grown on farm
f
(FF/ha)
yield of energy crop
d
grown on farm
f
(tons/ha)
subsidy paid to farmers for energy crop
d
(FF/ha)
production cost for energy crop
d
on farm
f
(FF/ha)
subsidy to land set aside (FF/ha)
multiplier used to scale up arable land of farm
f
to the national level
total arable land available on farm
f
(ha)
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